When a person dials the emergency telephone number “911” it is often in order to report an emergency associated with the person making the call. Ordinarily, such telephone calls are routed to a local municipality 911 dispatcher. This dispatcher has important responsibilities, and it is desirable to give that person as much information as possible in order to allow a reasoned judgment. Among the pieces of information that may be useful to a 911 dispatcher is the location of the telephone from which the call originates. Local 911 dispatch centers which handle emergency calls relay on Automatic Number Generation (ANI) (commonly referred to as “caller identification” or “caller ID) and Automatic Location Information (ALI) data, both generated by the telephone company, to locate the source (address, apartment number, cell phone, etc.) of the emergency call. The ANI and ALI information is used by the local 911 dispatch center to identify those emergency response resources available near the location of the originator of the emergency call, and to route the appropriate resources to the scene.
The location of the origin of a call to a 911 dispatch center is often difficult, as in those cases in which the telephone connection goes dead during the call, the caller has difficulty in assessing his location, or in reporting the location. Deaf andor dumb callers may present especial difficulties.
Many large businesses establish their operations in large office buildings or in groups of office buildings or building complexes (campus). Such campuses may have dozens or hundreds of telephone extensions which communicate with the outside world (the plain old telephone service or POTS) by means of one or more private business exchanges (PBX).
When an emergency number such as “911” is dialed by an extension within the campus and the call is routed by a PBX to POTS, the only ANI information made available to the 911 dispatcher or other emergency worker is a general telephone number for the campus, and not for the individual source extension within the campus. Similarly, the only ALI information is the formal address of the campus. The general telephone number of the campus and its formal address will often be insufficient to quickly identify the location of a caller to the emergency service. That caller may be in the basement of a remote building in the campus, or in any of hundreds if not thousands of office, laboratory, or workplace locations within the campus.
The difficulty in quickly locating the origin of a telephone call to an emergency service may be of life-or-death importance in some situations. If the caller cannot determine his location and communicate it verbally to the dispatcher, the response time of the emergency service will be severely impaired.
In many building complex or campus situations, there will be an on-site public safety answering point (PSAP) different from the municipality emergency service. Emergency calls originating within the campus may be routed by the PBX to the public safety answering point for immediate action. Such public safety answering points may have their own emergency numbers different from “911,” but may also respond to “911.” The emergency response personnel who answer the emergency calls from the PBX have the same problem of locating the source of the call as does the municipal 911 dispatcher. Many PBX installations, especially older installations, do not provide automatic number identification and location information.
Improved or alternative methods are desired for responding to emergency telephone calls.